/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jacky.lanlan.song.system;

import java.io.File;

import org.apache.log4j.Logger;

/**
 * <p>
 * Helpers for <code>java.lang.System</code>.
 * </p>
 * 
 * <p>
 * If a system property cannot be read due to security restrictions, the
 * corresponding field in this class will be set to <code>null</code> and a
 * message will be written to <code>System.err</code>.
 * </p>
 * 
 * @author Based on code from Avalon Excalibur
 * @author Based on code from Lucene
 * @author Stephen Colebourne
 * @author <a href="mailto:sdowney@panix.com">Steve Downey</a>
 * @author Gary Gregory
 * @author Michael Becke
 * @author Tetsuya Kaneuchi
 * @author Rafal Krupinski
 * @author Jason Gritman
 * @since 1.0
 * @version $Id: SystemUtils.java 437554 2006-08-28 06:21:41Z bayard $
 */
public abstract class SystemUtils {
	/** Prefix for system property placeholders: "${" */
	public static final String PLACEHOLDER_PREFIX = "${";
	
	/** Suffix for system property placeholders: "}" */
	public static final String PLACEHOLDER_SUFFIX = "}";
	
	private static final Logger logger = Logger.getLogger(SystemUtils.class);

	/**
   * The prefix String for all Windows OS.
   */
	private static final String OS_NAME_WINDOWS_PREFIX = "Windows";

	// System property constants
	// -----------------------------------------------------------------------
	// These MUST be declared first. Other constants depend on this.

	/**
   * The System property key for the user home directory.
   */
	private static final String USER_HOME_KEY = "user.home";

	/**
   * The System property key for the user directory.
   */
	private static final String USER_DIR_KEY = "user.dir";

	/**
   * The System property key for the Java IO temporary directory.
   */
	private static final String JAVA_IO_TMPDIR_KEY = "java.io.tmpdir";

	/**
   * The System property key for the Java home directory.
   */
	private static final String JAVA_HOME_KEY = "java.home";

	/**
   * <p>
   * The <code>awt.toolkit</code> System Property.
   * </p>
   * <p>
   * Holds a class name, on Windows XP this is
   * <code>sun.awt.windows.WToolkit</code>.
   * </p>
   * <p>
   * <b>On platforms without a GUI, this value is <code>null</code>.</b>
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.1
   */
	public static final String AWT_TOOLKIT = getSystemProperty("awt.toolkit");

	/**
   * <p>
   * The <code>file.encoding</code> System Property.
   * </p>
   * <p>
   * File encoding, such as <code>Cp1252</code>.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.0
   * @since Java 1.2
   */
	public static final String FILE_ENCODING = getSystemProperty("file.encoding");

	/**
   * <p>
   * The <code>file.separator</code> System Property. File separator (<code>&quot;/&quot;</code>
   * on UNIX).
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String FILE_SEPARATOR = getSystemProperty("file.separator");

	/**
   * <p>
   * The <code>java.awt.fonts</code> System Property.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.1
   */
	public static final String JAVA_AWT_FONTS = getSystemProperty("java.awt.fonts");

	/**
   * <p>
   * The <code>java.awt.graphicsenv</code> System Property.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.1
   */
	public static final String JAVA_AWT_GRAPHICSENV = getSystemProperty("java.awt.graphicsenv");

	/**
   * <p>
   * The <code>java.awt.headless</code> System Property. The value of this
   * property is the String <code>"true"</code> or <code>"false"</code>.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @see #isJavaAwtHeadless()
   * @since 2.1
   * @since Java 1.4
   */
	public static final String JAVA_AWT_HEADLESS = getSystemProperty("java.awt.headless");

	/**
   * <p>
   * The <code>java.awt.printerjob</code> System Property.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.1
   */
	public static final String JAVA_AWT_PRINTERJOB = getSystemProperty("java.awt.printerjob");

	/**
   * <p>
   * The <code>java.class.path</code> System Property. Java class path.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String JAVA_CLASS_PATH = getSystemProperty("java.class.path");

	/**
   * <p>
   * The <code>java.class.version</code> System Property. Java class format
   * version number.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String JAVA_CLASS_VERSION = getSystemProperty("java.class.version");

	/**
   * <p>
   * The <code>java.compiler</code> System Property. Name of JIT compiler to
   * use. First in JDK version 1.2. Not used in Sun JDKs after 1.2.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2. Not used in Sun versions after 1.2.
   */
	public static final String JAVA_COMPILER = getSystemProperty("java.compiler");

	/**
   * <p>
   * The <code>java.endorsed.dirs</code> System Property. Path of endorsed
   * directory or directories.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.4
   */
	public static final String JAVA_ENDORSED_DIRS = getSystemProperty("java.endorsed.dirs");

	/**
   * <p>
   * The <code>java.ext.dirs</code> System Property. Path of extension
   * directory or directories.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.3
   */
	public static final String JAVA_EXT_DIRS = getSystemProperty("java.ext.dirs");

	/**
   * <p>
   * The <code>java.home</code> System Property. Java installation directory.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String JAVA_HOME = getSystemProperty(JAVA_HOME_KEY);

	/**
   * <p>
   * The <code>java.io.tmpdir</code> System Property. Default temp file path.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_IO_TMPDIR = getSystemProperty(JAVA_IO_TMPDIR_KEY);

	/**
   * <p>
   * The <code>java.library.path</code> System Property. List of paths to
   * search when loading libraries.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_LIBRARY_PATH = getSystemProperty("java.library.path");

	/**
   * <p>
   * The <code>java.runtime.name</code> System Property. Java Runtime
   * Environment name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.0
   * @since Java 1.3
   */
	public static final String JAVA_RUNTIME_NAME = getSystemProperty("java.runtime.name");

	/**
   * <p>
   * The <code>java.runtime.version</code> System Property. Java Runtime
   * Environment version.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.0
   * @since Java 1.3
   */
	public static final String JAVA_RUNTIME_VERSION = getSystemProperty("java.runtime.version");

	/**
   * <p>
   * The <code>java.specification.name</code> System Property. Java Runtime
   * Environment specification name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_SPECIFICATION_NAME = getSystemProperty("java.specification.name");

	/**
   * <p>
   * The <code>java.specification.vendor</code> System Property. Java Runtime
   * Environment specification vendor.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_SPECIFICATION_VENDOR = getSystemProperty("java.specification.vendor");

	/**
   * <p>
   * The <code>java.specification.version</code> System Property. Java Runtime
   * Environment specification version.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.3
   */
	public static final String JAVA_SPECIFICATION_VERSION = getSystemProperty("java.specification.version");

	/**
   * <p>
   * The <code>java.util.prefs.PreferencesFactory</code> System Property. A
   * class name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.1
   * @since Java 1.4
   */
	public static final String JAVA_UTIL_PREFS_PREFERENCES_FACTORY = getSystemProperty("java.util.prefs.PreferencesFactory");

	/**
   * <p>
   * The <code>java.vendor</code> System Property. Java vendor-specific
   * string.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String JAVA_VENDOR = getSystemProperty("java.vendor");

	/**
   * <p>
   * The <code>java.vendor.url</code> System Property. Java vendor URL.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String JAVA_VENDOR_URL = getSystemProperty("java.vendor.url");

	/**
   * <p>
   * The <code>java.version</code> System Property. Java version number.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String JAVA_VERSION = getSystemProperty("java.version");

	/**
   * <p>
   * The <code>java.vm.info</code> System Property. Java Virtual Machine
   * implementation info.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.0
   * @since Java 1.2
   */
	public static final String JAVA_VM_INFO = getSystemProperty("java.vm.info");

	/**
   * <p>
   * The <code>java.vm.name</code> System Property. Java Virtual Machine
   * implementation name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_VM_NAME = getSystemProperty("java.vm.name");

	/**
   * <p>
   * The <code>java.vm.specification.name</code> System Property. Java Virtual
   * Machine specification name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_VM_SPECIFICATION_NAME = getSystemProperty("java.vm.specification.name");

	/**
   * <p>
   * The <code>java.vm.specification.vendor</code> System Property. Java
   * Virtual Machine specification vendor.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_VM_SPECIFICATION_VENDOR = getSystemProperty("java.vm.specification.vendor");

	/**
   * <p>
   * The <code>java.vm.specification.version</code> System Property. Java
   * Virtual Machine specification version.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_VM_SPECIFICATION_VERSION = getSystemProperty("java.vm.specification.version");

	/**
   * <p>
   * The <code>java.vm.vendor</code> System Property. Java Virtual Machine
   * implementation vendor.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_VM_VENDOR = getSystemProperty("java.vm.vendor");

	/**
   * <p>
   * The <code>java.vm.version</code> System Property. Java Virtual Machine
   * implementation version.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.2
   */
	public static final String JAVA_VM_VERSION = getSystemProperty("java.vm.version");

	/**
   * <p>
   * The <code>line.separator</code> System Property. Line separator (<code>&quot;\n&quot;</code>
   * on UNIX).
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String LINE_SEPARATOR = getSystemProperty("line.separator");

	/**
   * <p>
   * The <code>os.arch</code> System Property. Operating system architecture.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String OS_ARCH = getSystemProperty("os.arch");

	/**
   * <p>
   * The <code>os.name</code> System Property. Operating system name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String OS_NAME = getSystemProperty("os.name");

	/**
   * <p>
   * The <code>os.version</code> System Property. Operating system version.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String OS_VERSION = getSystemProperty("os.version");

	/**
   * <p>
   * The <code>path.separator</code> System Property. Path separator (<code>&quot;:&quot;</code>
   * on UNIX).
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String PATH_SEPARATOR = getSystemProperty("path.separator");

	/**
   * <p>
   * The <code>user.country</code> or <code>user.region</code> System
   * Property. User's country code, such as <code>GB</code>. First in JDK
   * version 1.2 as <code>user.region</code>. Renamed to
   * <code>user.country</code> in 1.4
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.0
   * @since Java 1.2
   */
	public static final String USER_COUNTRY = getSystemProperty("user.country") == null ? getSystemProperty("user.region")
			: getSystemProperty("user.country");

	/**
   * <p>
   * The <code>user.dir</code> System Property. User's current working
   * directory.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String USER_DIR = getSystemProperty(USER_DIR_KEY);

	/**
   * <p>
   * The <code>user.home</code> System Property. User's home directory.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String USER_HOME = getSystemProperty(USER_HOME_KEY);

	/**
   * <p>
   * The <code>user.language</code> System Property. User's language code,
   * such as <code>"en"</code>.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.0
   * @since Java 1.2
   */
	public static final String USER_LANGUAGE = getSystemProperty("user.language");

	/**
   * <p>
   * The <code>user.name</code> System Property. User's account name.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since Java 1.1
   */
	public static final String USER_NAME = getSystemProperty("user.name");

	/**
   * <p>
   * The <code>user.timezone</code> System Property. For example:
   * <code>"America/Los_Angeles"</code>.
   * </p>
   * 
   * <p>
   * Defaults to <code>null</code> if the runtime does not have security
   * access to read this property or the property does not exist.
   * </p>
   * 
   * <p>
   * This value is initialized when the class is loaded. If
   * {@link System#setProperty(String,String)} or
   * {@link System#setProperties(java.util.Properties)} is called after this
   * class is loaded, the value will be out of sync with that System property.
   * </p>
   * 
   * @since 2.1
   */
	public static final String USER_TIMEZONE = getSystemProperty("user.timezone");

	// Java version
	// -----------------------------------------------------------------------
	// This MUST be declared after those above as it depends on the
	// values being set up

	/**
   * <p>
   * Gets the Java version as a <code>String</code> trimming leading letters.
   * </p>
   * 
   * <p>
   * The field will return <code>null</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.1
   */
	public static final String JAVA_VERSION_TRIMMED = getJavaVersionTrimmed();

	// Java version values
	// -----------------------------------------------------------------------
	// These MUST be declared after the trim above as they depend on the
	// value being set up

	/**
   * <p>
   * Gets the Java version as a <code>float</code>.
   * </p>
   * 
   * <p>
   * Example return values:
   * </p>
   * <ul>
   * <li><code>1.2f</code> for JDK 1.2
   * <li><code>1.31f</code> for JDK 1.3.1
   * </ul>
   * 
   * <p>
   * The field will return zero if {@link #JAVA_VERSION} is <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final float JAVA_VERSION_FLOAT = getJavaVersionAsFloat();

	/**
   * <p>
   * Gets the Java version as an <code>int</code>.
   * </p>
   * 
   * <p>
   * Example return values:
   * </p>
   * <ul>
   * <li><code>120</code> for JDK 1.2
   * <li><code>131</code> for JDK 1.3.1
   * </ul>
   * 
   * <p>
   * The field will return zero if {@link #JAVA_VERSION} is <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final int JAVA_VERSION_INT = getJavaVersionAsInt();

	// Java version checks
	// -----------------------------------------------------------------------
	// These MUST be declared after those above as they depend on the
	// values being set up

	/**
   * <p>
   * Is <code>true</code> if this is Java version 1.1 (also 1.1.x versions).
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   */
	public static final boolean IS_JAVA_1_1 = getJavaVersionMatches("1.1");

	/**
   * <p>
   * Is <code>true</code> if this is Java version 1.2 (also 1.2.x versions).
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   */
	public static final boolean IS_JAVA_1_2 = getJavaVersionMatches("1.2");

	/**
   * <p>
   * Is <code>true</code> if this is Java version 1.3 (also 1.3.x versions).
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   */
	public static final boolean IS_JAVA_1_3 = getJavaVersionMatches("1.3");

	/**
   * <p>
   * Is <code>true</code> if this is Java version 1.4 (also 1.4.x versions).
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   */
	public static final boolean IS_JAVA_1_4 = getJavaVersionMatches("1.4");

	/**
   * <p>
   * Is <code>true</code> if this is Java version 1.5 (also 1.5.x versions).
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   */
	public static final boolean IS_JAVA_1_5 = getJavaVersionMatches("1.5");

	/**
   * <p>
   * Is <code>true</code> if this is Java version 1.6 (also 1.6.x versions).
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if {@link #JAVA_VERSION} is
   * <code>null</code>.
   * </p>
   */
	public static final boolean IS_JAVA_1_6 = getJavaVersionMatches("1.6");

	// Operating system checks
	// -----------------------------------------------------------------------
	// These MUST be declared after those above as they depend on the
	// values being set up
	// OS names from http://www.vamphq.com/os.html
	// Selected ones included - please advise commons-dev@jakarta.apache.org
	// if you want another added or a mistake corrected

	/**
   * <p>
   * Is <code>true</code> if this is AIX.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_AIX = getOSMatches("AIX");

	/**
   * <p>
   * Is <code>true</code> if this is HP-UX.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_HP_UX = getOSMatches("HP-UX");

	/**
   * <p>
   * Is <code>true</code> if this is Irix.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_IRIX = getOSMatches("Irix");

	/**
   * <p>
   * Is <code>true</code> if this is Linux.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_LINUX = getOSMatches("Linux")
			|| getOSMatches("LINUX");

	/**
   * <p>
   * Is <code>true</code> if this is Mac.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_MAC = getOSMatches("Mac");

	/**
   * <p>
   * Is <code>true</code> if this is Mac.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_MAC_OSX = getOSMatches("Mac OS X");

	/**
   * <p>
   * Is <code>true</code> if this is OS/2.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_OS2 = getOSMatches("OS/2");

	/**
   * <p>
   * Is <code>true</code> if this is Solaris.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_SOLARIS = getOSMatches("Solaris");

	/**
   * <p>
   * Is <code>true</code> if this is SunOS.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_SUN_OS = getOSMatches("SunOS");

	/**
   * <p>
   * Is <code>true</code> if this is a POSIX compilant system, as in any of
   * AIX, HP-UX, Irix, Linux, MacOSX, Solaris or SUN OS.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.1
   */
	public static final boolean IS_OS_UNIX = IS_OS_AIX || IS_OS_HP_UX
			|| IS_OS_IRIX || IS_OS_LINUX || IS_OS_MAC_OSX || IS_OS_SOLARIS
			|| IS_OS_SUN_OS;

	/**
   * <p>
   * Is <code>true</code> if this is Windows.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS = getOSMatches(OS_NAME_WINDOWS_PREFIX);

	/**
   * <p>
   * Is <code>true</code> if this is Windows 2000.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS_2000 = getOSMatches(
			OS_NAME_WINDOWS_PREFIX, "5.0");

	/**
   * <p>
   * Is <code>true</code> if this is Windows 95.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS_95 = getOSMatches(
			OS_NAME_WINDOWS_PREFIX + " 9", "4.0");

	// JDK 1.2 running on Windows98 returns 'Windows 95', hence the above

	/**
   * <p>
   * Is <code>true</code> if this is Windows 98.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS_98 = getOSMatches(
			OS_NAME_WINDOWS_PREFIX + " 9", "4.1");

	// JDK 1.2 running on Windows98 returns 'Windows 95', hence the above

	/**
   * <p>
   * Is <code>true</code> if this is Windows ME.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS_ME = getOSMatches(
			OS_NAME_WINDOWS_PREFIX, "4.9");

	// JDK 1.2 running on WindowsME may return 'Windows 95', hence the above

	/**
   * <p>
   * Is <code>true</code> if this is Windows NT.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS_NT = getOSMatches(OS_NAME_WINDOWS_PREFIX
			+ " NT");

	// Windows 2000 returns 'Windows 2000' but may suffer from same JDK1.2 problem

	/**
   * <p>
   * Is <code>true</code> if this is Windows XP.
   * </p>
   * 
   * <p>
   * The field will return <code>false</code> if <code>OS_NAME</code> is
   * <code>null</code>.
   * </p>
   * 
   * @since 2.0
   */
	public static final boolean IS_OS_WINDOWS_XP = getOSMatches(
			OS_NAME_WINDOWS_PREFIX, "5.1");

	// -----------------------------------------------------------------------
	/**
   * <p>
   * Gets the Java version number as a <code>float</code>.
   * </p>
   * 
   * <p>
   * Example return values:
   * </p>
   * <ul>
   * <li><code>1.2f</code> for JDK 1.2
   * <li><code>1.31f</code> for JDK 1.3.1
   * </ul>
   * 
   * <p>
   * Patch releases are not reported. Zero is returned if
   * {@link #JAVA_VERSION_TRIMMED} is <code>null</code>.
   * </p>
   * 
   * @return the version, for example 1.31f for JDK 1.3.1
   */
	private static float getJavaVersionAsFloat() {
		if (JAVA_VERSION_TRIMMED == null) { return 0f; }
		String str = JAVA_VERSION_TRIMMED.substring(0, 3);
		if (JAVA_VERSION_TRIMMED.length() >= 5) {
			str = str + JAVA_VERSION_TRIMMED.substring(4, 5);
		}
		try {
			return Float.parseFloat(str);
		}
		catch (Exception ex) {
			return 0;
		}
	}

	/**
   * <p>
   * Gets the Java version number as an <code>int</code>.
   * </p>
   * 
   * <p>
   * Example return values:
   * </p>
   * <ul>
   * <li><code>120</code> for JDK 1.2
   * <li><code>131</code> for JDK 1.3.1
   * </ul>
   * 
   * <p>
   * Patch releases are not reported. Zero is returned if
   * {@link #JAVA_VERSION_TRIMMED} is <code>null</code>.
   * </p>
   * 
   * @return the version, for example 131 for JDK 1.3.1
   */
	private static int getJavaVersionAsInt() {
		if (JAVA_VERSION_TRIMMED == null) { return 0; }
		String str = JAVA_VERSION_TRIMMED.substring(0, 1);
		str = str + JAVA_VERSION_TRIMMED.substring(2, 3);
		if (JAVA_VERSION_TRIMMED.length() >= 5) {
			str = str + JAVA_VERSION_TRIMMED.substring(4, 5);
		} else {
			str = str + "0";
		}
		try {
			return Integer.parseInt(str);
		}
		catch (Exception ex) {
			return 0;
		}
	}

	/**
   * Trims the text of the java version to start with numbers.
   * 
   * @return the trimmed java version
   */
	private static String getJavaVersionTrimmed() {
		if (JAVA_VERSION != null) {
			for (int i = 0; i < JAVA_VERSION.length(); i++) {
				char ch = JAVA_VERSION.charAt(i);
				if (ch >= '0' && ch <= '9') { return JAVA_VERSION.substring(i); }
			}
		}
		return null;
	}

	/**
   * <p>
   * Decides if the java version matches.
   * </p>
   * 
   * @param versionPrefix
   *          the prefix for the java version
   * @return true if matches, or false if not or can't determine
   */
	private static boolean getJavaVersionMatches(String versionPrefix) {
		if (JAVA_VERSION_TRIMMED == null) { return false; }
		return JAVA_VERSION_TRIMMED.startsWith(versionPrefix);
	}

	/**
   * <p>
   * Decides if the operating system matches.
   * </p>
   * 
   * @param osNamePrefix
   *          the prefix for the os name
   * @return true if matches, or false if not or can't determine
   */
	private static boolean getOSMatches(String osNamePrefix) {
		if (OS_NAME == null) { return false; }
		return OS_NAME.startsWith(osNamePrefix);
	}

	/**
   * <p>
   * Decides if the operating system matches.
   * </p>
   * 
   * @param osNamePrefix
   *          the prefix for the os name
   * @param osVersionPrefix
   *          the prefix for the version
   * @return true if matches, or false if not or can't determine
   */
	private static boolean getOSMatches(String osNamePrefix,
			String osVersionPrefix) {
		if (OS_NAME == null || OS_VERSION == null) { return false; }
		return OS_NAME.startsWith(osNamePrefix)
				&& OS_VERSION.startsWith(osVersionPrefix);
	}

	// -----------------------------------------------------------------------
	/**
   * <p>
   * Gets a System property, defaulting to <code>null</code> if the property
   * cannot be read.
   * </p>
   * 
   * <p>
   * If a <code>SecurityException</code> is caught, the return value is
   * <code>null</code> and a message is written to <code>System.err</code>.
   * </p>
   * 
   * @param property
   *          the system property name
   * @return the system property value or <code>null</code> if a security
   *         problem occurs
   */
	private static String getSystemProperty(String property) {
		try {
			return System.getProperty(property);
		}
		catch (SecurityException ex) {
			// we are not allowed to look at this property
			System.err
					.println("Caught a SecurityException reading the system property '"
							+ property
							+ "'; the SystemUtils property value will default to null.");
			return null;
		}
	}

	/**
   * <p>
   * Is the Java version at least the requested version.
   * </p>
   * 
   * <p>
   * Example input:
   * </p>
   * <ul>
   * <li><code>1.2f</code> to test for JDK 1.2</li>
   * <li><code>1.31f</code> to test for JDK 1.3.1</li>
   * </ul>
   * 
   * @param requiredVersion
   *          the required version, for example 1.31f
   * @return <code>true</code> if the actual version is equal or greater than
   *         the required version
   */
	public static boolean isJavaVersionAtLeast(float requiredVersion) {
		return JAVA_VERSION_FLOAT >= requiredVersion;
	}

	/**
   * <p>
   * Is the Java version at least the requested version.
   * </p>
   * 
   * <p>
   * Example input:
   * </p>
   * <ul>
   * <li><code>120</code> to test for JDK 1.2 or greater</li>
   * <li><code>131</code> to test for JDK 1.3.1 or greater</li>
   * </ul>
   * 
   * @param requiredVersion
   *          the required version, for example 131
   * @return <code>true</code> if the actual version is equal or greater than
   *         the required version
   * @since 2.0
   */
	public static boolean isJavaVersionAtLeast(int requiredVersion) {
		return JAVA_VERSION_INT >= requiredVersion;
	}

	/**
   * Returns whether the {@link #JAVA_AWT_HEADLESS} value is <code>true</code>.
   * 
   * @return <code>true</code> if <code>JAVA_AWT_HEADLESS</code> is
   *         <code>"true"</code>, <code>false</code> otherwise.
   * 
   * @see #JAVA_AWT_HEADLESS
   * @since 2.1
   * @since Java 1.4
   */
	public static boolean isJavaAwtHeadless() {
		return JAVA_AWT_HEADLESS != null ? JAVA_AWT_HEADLESS.equals(Boolean.TRUE
				.toString()) : false;
	}

	/**
   * <p>
   * Gets the Java home directory as a <code>File</code>.
   * </p>
   * 
   * @return a directory
   * @throws SecurityException
   *           if a security manager exists and its
   *           <code>checkPropertyAccess</code> method doesn't allow access to
   *           the specified system property.
   * @see System#getProperty(String)
   * @since 2.1
   */
	public static File getJavaHome() {
		return new File(System.getProperty(JAVA_HOME_KEY));
	}

	/**
   * <p>
   * Gets the Java IO temporary directory as a <code>File</code>.
   * </p>
   * 
   * @return a directory
   * @throws SecurityException
   *           if a security manager exists and its
   *           <code>checkPropertyAccess</code> method doesn't allow access to
   *           the specified system property.
   * @see System#getProperty(String)
   * @since 2.1
   */
	public static File getJavaIoTmpDir() {
		return new File(System.getProperty(JAVA_IO_TMPDIR_KEY));
	}

	/**
   * <p>
   * Gets the user directory as a <code>File</code>.
   * </p>
   * 
   * @return a directory
   * @throws SecurityException
   *           if a security manager exists and its
   *           <code>checkPropertyAccess</code> method doesn't allow access to
   *           the specified system property.
   * @see System#getProperty(String)
   * @since 2.1
   */
	public static File getUserDir() {
		return new File(System.getProperty(USER_DIR_KEY));
	}

	/**
   * <p>
   * Gets the user home directory as a <code>File</code>.
   * </p>
   * 
   * @return a directory
   * @throws SecurityException
   *           if a security manager exists and its
   *           <code>checkPropertyAccess</code> method doesn't allow access to
   *           the specified system property.
   * @see System#getProperty(String)
   * @since 2.1
   */
	public static File getUserHome() {
		return new File(System.getProperty(USER_HOME_KEY));
	}

	/**
	 * Resolve ${...} placeholders in the given text, replacing them with
	 * corresponding system property values.
	 * 
	 * @param text
	 *          the String to resolve
	 * @return the resolved String
	 * @see #PLACEHOLDER_PREFIX
	 * @see #PLACEHOLDER_SUFFIX
	 */
	public static String resolvePlaceholders(String text) {
		StringBuffer buf = new StringBuffer(text);
		
		int startIndex = buf.indexOf(PLACEHOLDER_PREFIX);
		while (startIndex != -1) {
			int endIndex = buf.indexOf(PLACEHOLDER_SUFFIX, startIndex + PLACEHOLDER_PREFIX.length());
			if (endIndex != -1) {
				String placeholder = buf.substring(startIndex + PLACEHOLDER_PREFIX.length(), endIndex);
				int nextIndex = endIndex + PLACEHOLDER_SUFFIX.length();
				try {
					String propVal = System.getProperty(placeholder);
					if (propVal == null) {
						// Fall back to searching the system environment.
						propVal = System.getenv(placeholder);
					}
					if (propVal != null) {
						buf.replace(startIndex, endIndex + PLACEHOLDER_SUFFIX.length(), propVal);
						nextIndex = startIndex + propVal.length();
					}
					else {
						if (logger.isInfoEnabled()) {
							logger.warn("Could not resolve placeholder '" + placeholder + "' in [" + text
									+ "] as system property: neither system property nor environment variable found");
						}
					}
				}
				catch (Throwable ex) {
					if (logger.isInfoEnabled()) {
						logger.warn("Could not resolve placeholder '" + placeholder + "' in [" + text + "] as system property: "
								+ ex);
					}
				}
				startIndex = buf.indexOf(PLACEHOLDER_PREFIX, nextIndex);
			}
			else {
				startIndex = -1;
			}
		}
		
		return buf.toString();
	}

}
